Rehydrating yeast

[Furynfear]

Hey peeps,

I did a search on the forums and came up with 2 results. In spirits do u rehydrate yeast.

Also I making a tpw 2moro and was wondering if I need to rehydrate the yeast. Lowans Bakers yeast.

[bt1]

No gain for a Lowans, simply pitch directly to a well aerated fermenter at mid 20~ish temp and away you go. pays to circulate wash before adding to disperse yeast.

For specialist yeasts , EC1118 for example without rehydrating in plain water they lag or fail badly.

bt1

[Furynfear]

What do you mean recirculate the wash.

[bt1]

simply stir it so it's moving... gradually add yeast, it will disperse better avoiding dry clumps of yeast, gives a more even start.

bt1

[Yummyrum]

For specialist yeasts , EC1118 for example without rehydrating in plain water they lag or fail badly.

bt1

Interesting point bt1 that could explain why I have had long lag times with EC1118

How long does it normally take to re-hydrate fully .My experience with hydrating was than most of the yeast just appeared to sink to the bottom and didn't really seem to change so after several hours I just pitched it and have never worried about it since........maybe I should

[OzKev]

Rehydrating yeast is just that, getting moisture into the cells. It should be limited to about 15mins, and you don't need a foaming monster at the end of it. Dropping to the bottom of the jar is ok. Rehydrating for too long can be detrimental to your yeast.

Creating a yeast starter is where you actively promote the yeast to take off fermenting.

[Furynfear]

Well they say the minute you throw dry yeast in you kill half if u don't rehydrate. I no they replicate but was just curious if that's why he went 80grams in the tpw recipe. Maybe you could go 40g is you rehydrated the yeast.

[Andy]

i always rehydrate my yeast, and I usually use Lowans. im not too sure bt1 thought behind it not needing it but ec-118 needing it

The suggested temperature from when a member emailed Lowans was 30 degrees, which is standard for most yeast.

Yummyrum- Rehydration only takes about 20mins- after several hours they would be starving!

[Furynfear]

i always rehydrate my yeast, and I usually use Lowans. im not too sure bt1 thought behind it not needing it but ec-118 needing it

The suggested temperature from when a member emailed Lowans was 30 degrees, which is standard for most yeast.

Yummyrum- Rehydration only takes about 20mins- after several hours they would be starving!

Hey mate how do u rehydrate the lowans. Step by step if u could. I've got the basics but a bit confused about it still

[Furynfear]

Watch "REHYDRATING DRIED YEAST" on YouTube
REHYDRATING DRIED YEAST: http://youtu.be/SL92Bd4kfbQ

What do u think of this.

[Andy]

i use about 2L of water. Ideally boil the water, then let it sit to cool down to 30 degrees. this is suppose to remove oxygen from it, but i usually just heat the water up to 30 degrees.
next poor the yeast in at let it sit in the warm water for 10-15mins. its best to do it in a pot that has a large surface area, otherwise they will just clump on top.
then give the yeast a swirl and let them sit for another 10-15 min.
then poor it into the wash.

I read a while ago that its best to rehydrate the yeast to plump up their cell walls before introducing them to the sugary environment, for this reason I don't add any sugar while rehydrating them (i know that some people do to start the yeast off)

[bt1]

Yum,

Had a fair bit of time with EC1118. Be wary the US market gold packeted product instructions sheet is not the same as the original spec sheet they send with batches to Aust.
I've settled on the following process based on the former spec sheet = matches my batch of EC1118.

Remove from fridge 15 mins prior to use
Spring water to 32c 200 300ml for 30gm = 60lt fermenter
Strongly aerate spring water, sprinkle yeast evenly across the swirling surface, it will sink as you mentioned.
After all sunk a very gentle stir, allow it 15mins. (More than 45min - hour yeast would stress with no food source).
Pitch temp must be within 5c to avoid thermal shock...
A gentle short stir into fermenter, lid off for first hour during early growth phase then lid on

Hope it helps
bt1

[Yummyrum]

Thanks for your replies.bt1 , why do you aerate water.Why does Andy think its best to have oxygen depleted water.

[OzKev]

I think Andy meant that you are supposed to boil the water to sanitize it, but that depletes the oxygen which is not good, so he just heats his to 30c.

From here
https://www.wyeastlab.com/he-yeast-fundamentals.cfm

Oxygen is used by yeast for synthesis of sterols and unsaturated fatty acids that are necessary growth factors. Without oxygen, these lipids can’t be biosynthesized and growth will be very limited. The sterols and fatty acids produced are also very important in the structure of the cell membrane and the ability of the yeast to respond to external and internal stresses. Adequate oxygen in the wort when the yeast is pitched is essential to a successful fermentation and long-term health of the culture.

[Andy]

the theory behind rehydrating in oxygen depleted water is that the yeast will not be active during rehydration. you are aiming for plumping up their cells, not starting cell production. putting them in oxygenate water could be damaging as their cells membranes are still fragile- and oxygen after all is toxic. once these membrane has rehydrate, add them to an oxygen rich environment will help increase the strength of cell membrane, and start cellular activity- which is why we aerate our washes

keep in mind that all these factors don't matter TOO much. its mostly personal preference/habit.

[Yummyrum]

OK so its one vote for oxygen and one vote against ......So I'll split the difference and just use some plain old filtered water at around close to the wash temp .Stick it in for 15-20 minuates then dump it in the wash :-D ........and pray :teasing-neener:

[Furynfear]

Yeast need oxygen to multiply. That's y u stir during rehydration

[bt1]

Yum,

Just make sure your close to 30 - 35c I use 32c for rehydrating the temp is needed to activate the little beasties....can cool to wort temp gradually if needed by small additions periodically of cool water.

Fury I would not support stirring a yeast slurry to oxygenate it. You'll do more damage than good. The water should be well aerated prior
This assists with fatty acid coating they spray onto yeast grains breakdown-dissolving.

bt1

[Andy]

Yeast need oxygen to multiply. That's y u stir during rehydration

correct- yeast need oxygen to multiply, but during rehydration they will not be multiplying. hence no oxygen required.

[OzKev]

Yeast DO NOT need oxygen during their reproduction phase (log phase). Yeast use oxygen in their lag phase in the preparation for reproducing, which rehydration plays part of.